Which is a DISCRETE random variable?

The number of movies you watch.

What is the 68-95-99.7 rule?

1 std dev (both sides) from the mean 68% of data, and so on

What is the definition of normal distribution

makes a symmetrical bell-shaped graph

What defines a random variable?

It looks at probability and changes or is unknown

Let X be a continuous random variable. What is the cumulative distribution function (CDF)?

F(x) = 1-P(X>x), F(x) = P(X≤x)

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Probability Density Function

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Questions 23

Answers

1
For a continuous uniform distribution the probability the probability density function, f(x)...
Represents the probability of x for all points
Increases as x increases
Has a graph that looks like a bell
Is equal at all points
2
What is the probability density function (PDF)?
f(x)=∫F(X)dx
f(X)=1-P(X>x)
f(x) = dF(X)/dx
3
In statistics, what does PDF stand for?
Probability Distribution Function
Probability Density Function
Printable Document Format
Periodic Distribution Function
4
If mean = 7 and variance = 9, what is the z-score for 6?
-0.11
-0.33
0.43
0.33
5
Which is a DISCRETE random variable?
The number of hours spent on production.
The length of a movie.
The weight of the lead actor.
The number of movies you watch.
6
What is the formula for a z-score?
z = (x - μ) / σ
Look it up in the table
z = mx + b
z = Σx / n
7
The values of the cumulative distribution function (CDF) is from 0 to 1
True
False
8
What is the 68-95-99.7 rule?
1 std dev (both sides) from the mean 68% of data, and so on
Ian has a 68 in Stat while Nick has a 95
68% of all data in the sample will be one std dev above mean
None of the above
9
What is the z-score formula?
(x- standard deviation)/mean
mean
(x-mean)/standard deviation
(mean-standard deviation)/ x
10
The area under the cumulative distribution function must integrate to 1.
False
True
11
What is the shape of the probability density function below?
Curved
Right Skewed
Symmetrical
Left Skewed
12
Is this a probability density function (PDF)?
NO
YES
13
What is the mean?
60
80
70
14
A normal probability distribution is:
discrete
continuous
uniform
categorical
15
What is the definition of normal distribution
circumstance, fact, or influence that contributes to outcome
obtained by multiplying quantities together
number that can be divided by another number w/o a remainder
makes a symmetrical bell-shaped graph
16
Which of the following is a continuous random variable?
number of people in this class
number of hours you sleep
number of classes you are taking
number of pets you own
17
What is the standard deviation of this Normal Distribution?
8
6
2
12
18
The 68-95-99.7 Rule is also known as the...
Empirical Rule
Emperor's Rule
Infernal Rule
Eupherical Rune
19
What defines a random variable?
It is random and deals with the x axis
It looks at probability and changes or is unknown
It can be described by the variable x
It varies or looks at chance
20
What cannot be true about a probability density function of a continuous random variable?
f(x) always above x-axis
area underneath f(x) = 1
f(x)<0
continuous
21
MEDIAN of Cumulative distribution function is
F(x) = 5.0
F(x) = 0.75
F(x) = 0.25
F(x) = 0.5
22
The empirical rule, also known as 68-95-99.7 rule, only applies to the:
uniform distribution
skewed distributions
normal distribution
bimodal distribution
23
Let X be a continuous random variable. What is the cumulative distribution function (CDF)?
F(x) = P(X>x)
F(x) = 1-P(X>x)
F(x)=df(X)/dx
F(x) = P(X≤x)

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